<!DOCTYPE html>
<title>Tests that the ascentOverride, descentOverride and lineGapOverride attributes of FontFace work</title>
<link rel="help" href="https://drafts.csswg.org/css-font-loading/#fontface-interface">
<link rel="help" href="https://drafts.csswg.org/css-fonts-4/#font-metrics-override-desc">
<link rel="match" href="fontface-override-descriptors-ref.html">
<script>
const face = new FontFace(
    'ahem-overridden',
    'local("Ahem"), url("/fonts/Ahem.ttf")',
    {ascentOverride: '100%', descentOverride: '100%', lineGapOverride: '100%'});
document.fonts.add(face);

// Line height is ascent + descent + lineGap = 3em
// Baseline is placed at lineGap * 0.5 + ascent = 1.5em below line box top
// Since each Ahem 'X' glyph has 0.8em above baseline, the top of each glyph
// should be placed at 0.7em below line box top
</script>
<style>
#target {
  position: absolute;
  font-family: ahem-overridden;
  font-size: 20px;
}
</style>

<div id="target">
  XXXXX<br>
  XXXXX
</div>
